Vehicle exhaust systems refers to the systems which can collecte and exhaust air,they were generally divided into the exhaust manifold, exhaust pipe, catalytic converter, exhaust temperature sensor, automotive muffler and exhaust tail pipe, etc.
The vehicle exhaust systems of the automobile exhaust system is mainly to discharge the exhaust gas from the engine, at the same time, the pollution of the exhaust gas is reduced, and the noise is reduced.Vehicle exhaust systems are mainly used for light vehicles, mini cars and buses, motorcycles and other motor vehicles.
The automobile is a comprehensive noise source which includes all kinds of noises. Due to the noise source of automobile is not completely sealed (there is only part of the sealed), so vehicle radiation noise decided to the sound source of the sound level, characteristics and their interaction.
The automobile noise source can be divided into the engine noise and the chassis noise,they are mainly related to the engine speed and the vehicle speed.
Engine noise is the main noise source of vehicle exhaust systems. Engine noise can be divided into aerodynamic noise, mechanical noise and combustion noise.
Air dynamic noise mainly includes inlet, exhaust and fan noise. This is due to the air intake, exhaust and fan rotation caused by the vibration of the air caused by noise, this part of the noise directly to the surrounding air radiation. In the absence of intake and exhaust muffler, exhaust noise is the biggest noise source of the engine, the intake noise is the second. Fan noise, especially in air - cooled internal combustion engines, is also one of the main sources of noise.
To reduce the noise of the sound source, first of all, we should understand the sound source noise mechanism and the rules, followed by improvement of the machine design, the use of advanced technology, causes a decrease of the exciting force of the noise, reduce system sounding components of exciting force response, and measures to improve the processing and assembly precision to achieve. Reduced excitation force includes:
To improve the accuracy of the dynamic balance of rotating parts, to lubricate moving parts, reduce the resonance friction; reduce the flow rate of various air flow noise sources, to avoid excessive turbulent flow.